Re: [PATCH] bpf: don't rely on GCC __attribute__((optimize)) to disable GCSE

[kernel test robot <lkp@intel.com>]

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In-Reply-To: <20201027205723.12514-1-ardb@kernel.org>
References: <20201027205723.12514-1-ardb@kernel.org>
TO: Ard Biesheuvel <ardb@kernel.org>
TO: linux-kernel(a)vger.kernel.org
CC: netdev(a)vger.kernel.org
CC: bpf(a)vger.kernel.org
CC: arnd(a)arndb.de
CC: Ard Biesheuvel <ardb@kernel.org>
CC: Nick Desaulniers <ndesaulniers@google.com>
CC: Arvind Sankar <nivedita@alum.mit.edu>
CC: Randy Dunlap <rdunlap@infradead.org>
CC: Josh Poimboeuf <jpoimboe@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>

Hi Ard,

I love your patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]
[also build test WARNING on bpf/master linus/master linux/master v5.10-rc1 next-20201027]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Ard-Biesheuvel/bpf-don-t-rely-on-GCC-__attribute__-optimize-to-disable-GCSE/20201028-045850
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-randconfig-a001-20201026 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project f2c25c70791de95d2466e09b5b58fc37f6ccd7a4)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/edebf279098c74782e939d735bd82311c0030968
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Ard-Biesheuvel/bpf-don-t-rely-on-GCC-__attribute__-optimize-to-disable-GCSE/20201028-045850
        git checkout edebf279098c74782e939d735bd82311c0030968
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> clang-12: warning: optimization flag '-fno-gcse' is not supported [-Wignored-optimization-argument]
   kernel/bpf/core.c:1358:12: warning: no previous prototype for function 'bpf_probe_read_kernel' [-Wmissing-prototypes]
   u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
              ^
   kernel/bpf/core.c:1358:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
   ^
   static 
   1 warning generated.

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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